Build Things on Top of ERDDAPThere are many features in ERDDAP that can be used by computer programs or scripts
that you write. You can use them to build other web applications or web services on
top of ERDDAP, making ERDDAP do most of the work!
So if you have an idea for a better interface to the data that ERDDAP serves or a web
page that needs an easy way to access data, we encourage you to build your own
web application, web service, or web page and use ERDDAP as the foundation.
Your system can get data, graphs, and other information from ERD's ERDDAP or from
other ERDDAP installations, or you can
set up your own ERDDAP server,
which can be
publicly accessible or just privately accessible.

RESTful URL RequestsRequests for user-interface information from ERDDAP (for example, search results)
use the web's universal standard for requests:
URLs
sent via
HTTP GET.
This is the same mechanism that your browser uses when you fill out a form
on a web page and click on Submit.
To use HTTP GET, you generate a specially formed URL (which may include a query)
and send it with HTTP GET. You can form these URLs by hand and enter them in
the address textfield of your browser (for example,
https://salishsea.eos.ubc.ca/erddap/search/index.json?page=1&itemsPerPage=1000&searchFor=temperature)
Or, you can write a computer program or web page script to create a URL, send it,
and get the response. URLs via HTTP GET were chosen because

A URL completely define a given request, so you can bookmark it in your browser,
write it in your notes, email it to a friend, etc.

Percent EncodingIn URLs, some characters are not allowed (for example, spaces) and other characters
have special meanings (for example, '&' separates key=value pairs in a query).
When you fill out a form on a web page and click on Submit, your browser automatically
percent encodes
the special characters in the URL (for example, space becomes %20), for example,
https://salishsea.eos.ubc.ca/erddap/search/index.html?page=1&itemsPerPage=1000&searchFor=temperature%20wind%20speedBut if your computer program or script generates the URLs, it probably needs to do the percent
encoding itself. If so, then probably all characters other than A-Za-z0-9_-!.~'()*
in the query's values (the parts after the '=' signs) need to be encoded
as %HH, where HH is the 2 digit hexadecimal value of the character, for example, space becomes %20.
Characters above #127 must be converted to UTF-8 bytes, then each UTF-8 byte must be percent encoded
(ask a programmer for help). Programming languages have tools to do this (for example, see Java's
java.net.URLEncoder and JavaScript's
encodeURIComponent()) and there are
web sites that percent encode/decode for you.

Requesting Compressed FilesERDDAP doesn't offer results stored in compressed (e.g., .zip or .gzip) files.
Instead, ERDDAP looks for
accept-encoding
in the HTTP GET request header sent
by the client. If a supported compression type ("gzip", "x-gzip", or "deflate") is found in the accept-encoding list, ERDDAP includes "content-encoding" in the HTTP response
header and compresses the data as it transmits it.
It is up to the client program to look for "content-encoding" and decompress the data.
Browsers and OPeNDAP clients do this by default. They request compressed data and
decompress the returned data automatically.
Other clients (e.g., Java programs) have to do this explicitly.

In every results table format (except .jsonlKVP, where column names are on every row):

Each column has a column name and one type of information.

The first row of the table has the column names.

Subsequent rows have the information you requested.

The content in these plain file types is also slightly different from the .html
response — it is intentionally bare-boned so that it is easier for a computer
program to work with.

A Consistent Data Structure for the ResponsesAll of the user-interface services described on this page can return a table of
data in any of the common file formats listed above. Hopefully, you can write
just one procedure to parse a table of data in one of the formats. Then you can
re-use that procedure to parse the response from any of these services. This
should make it easier to deal with ERDDAP.

If a datum in a .csv file has internal double quotes or commas, ERDDAP follows the
.csv specification strictly: it puts double quotes around the datum and doubles
the internal double quotes.

Special characters in a .csv or .tsv file are encoded like
JSON
backslash-encoded
characters: \n (newline), \\ (backslash), \f (formfeed), \t (tab), \r (carriage return)
or with the \uhhhh syntax.

jsonpRequests for .json files may now include an optional jsonp request by
adding "&.jsonp=functionName" to the end of the query. Basically, this tells
ERDDAP to add "functionName(" to the beginning of the response and ")" to the
end of the response. The first character of functionName must be an ISO 8859 letter or "_".
Each optional subsequent character must be an ISO 8859 letter, "_", a digit, or ".".
If originally there was no query, leave off the "&" in your query.

griddap and tabledap Offer Different File Types
The file types listed above are file types ERDDAP can use to respond to
user-interface types of requests (for example, search requests). ERDDAP supports
a different set of file types for scientific data (for example, satellite and buoy
data) requests (see the
griddap and
tabledap
documentation).

The Data Access Forms are just simple web pages to generate URLs which
request data (for example, satellite and buoy data). The data can be in any of
several common file formats. Your program can generate these URLs directly.
For more information, see the
griddap documentation and
tabledap documentation.

The Make A Graph pages are just simple web pages to generate URLs which
request graphs of a subset of the data. The graphs can be in any of several
common file formats. Your program can generate these URLs directly. For
more information, see the
griddap documentation and
tabledap documentation.

ERDDAP has a special tabular dataset called
allDatasets
which has data about all of the datasets currently available in
this ERDDAP. There is a row for each dataset. There are columns with
different types of information (for example, datasetID, title, summary,
institution, license, Data Access Form URL, Make A Graph URL).
Because this is a tabledap dataset,
you can use a tabledap data request to request
specific columns and rows which match the constraints, and you can
get the response in whichever reponse file type you prefer,
for example, .html, .xhtml, .csv, .json, .jsonlCSV, or .jsonlKVP.

As described above, since Java programs can access data available on the web, you can
write a Java program that accesses data from any publicly accessible ERDDAP installation.

Or, since ERDDAP is an all-open source program, you can also set up your own copy of
ERDDAP on your own server (publicly accessible or not) to serve your own data. Your Java
programs can get data from that copy of ERDDAP. See
Set Up Your Own ERDDAP.

Many ERDDAP installations don't have authentication enabled and thus
don't provide any way for users to login, nor do they have any private datasets.

Some ERDDAP installations do have authentication enabled.
Currently, ERDDAP only supports authentication via Google-managed email accounts,
which includes email accounts at NOAA and many universities.
If an ERDDAP has authentication enabled, anyone with a Google-managed email account
can log in, but they will only have access to the private datasets
that the ERDDAP administrator has explicitly authorized them to access.
For instructions on logging into ERDDAP from a browser or via a script, see
Access to Private Datasets in ERDDAP.

If you want to use a new feature on a remote ERDDAP, you can find out if the new
feature is available by sending a request to determine the ERDDAP's version
number, for example,
https://salishsea.eos.ubc.ca/erddap/versionERDDAP will send a text response with the ERDDAP version number of that ERDDAP.
For example:
ERDDAP_version=1.82If you get an HTTP 404 Not-Found error message, treat the ERDDAP as version
1.22 or lower.

Or, you can request the version_string, which may have additional information.
For example,
https://salishsea.eos.ubc.ca/erddap/version_stringERDDAP will send a text response with the ERDDAP version_string of that ERDDAP.
It will be a floating point number (the version number)
with an optional suffix of '_' plus additional ASCII text (no spaces or control characters).
For example:
ERDDAP_version_string=1.82_JohnsForkIf you get an HTTP 404 Not-Found error message, treat the ERDDAP as version
1.80 or lower.